Low-pressure chill-casting devices

ABSTRACT

A device for chill-moulding light alloy castings under lowpressure conditions, which comprises a fluid-tight enclosure, a crucible disposed within said enclosure and adapted to be filled with molten metal, a mould made of several sections assembled either to the upper plate or to the lower plate of a press, a casting tube and its joint means providing a fluid connection between said crucible and said mould, said device operating in response to the development of the air pressure within said enclosure so as to force the molten metal from said crucible into said mould through said casting tube, means for developing the air pressure within said enclosure, characterized in that said fluid-tight enclosure and said moulding device consist of two separate sections movable in relation to each other and interconnected through a casting duct and its connecting tube both easy to remove and heat.

United States Patent 1191 Chatourel et al.

1451 Apr. 17, 1973 [s41 LOW-PRESSURE CHILL-CASTING OTHER PUBLICATIQNS DEVICES Example 402, pg. 330, Metals Handbook, Vol. 5, [75] Inventors: Pierre Rene Chatourel; Jean Henri Fgrging d C tin January, 1970.

Lefebvre, both of Billancourt, France Primary Examiner-J. Spencer Overholser [73] Assignee: Regie Nationale Des Usines Renault, Assistant Examiner john Roethel Binancolm (Hams de Seine), Att0mey-Stevens, Davis, Miller & Mosher France [22] Filed: June 22, 1970 [57] CT A device for chill-moulding light alloy castings under Appl' 47978 low-pressure conditions, which comprises a fluid-tight enclosure, 21 crucible disposed within said enclosure [30] Foreign Applica ion riori y a and adapted to be filled with molten metal, a mould Aug. 6 1969 France ..6927058 made Several secfims assembled either to the upper plate or to the lower plate of a press, a casting tube 52 us. (:1. ..164/306, 164/119, 164/337 and its joint means providing a fluid connection 51 1m.c1. ..B22d 17/06 between said crucible and Said. mould, said device [58] Field 61 Search ..164/113, 119, 130, p ng in response to h d velopment of the air 164/133, 136, 303, 306, 307, 308,309, 310, pressure within said enclosure so as to force the mol- 3] I, 335, 337, 129; 18/30 LD, 30 LM, 30 LF ten metal from said crucible into said mould through said casting tube, means for developing the air pres- [56] References Cited sure within said enclosure, characterized in that said fluid-tight enclosure and said'moulding device consist UNITED STATES PATENTS Y of two separate sections movable in relation to each 2,131,955 10/1938 Johnson ..l64/311 other and interconnected through a casting duct and 2,847,739 8/1958 Sylvester 164/1 19 its connecting tube both easy to remove and heat. 2,119,242 5/1938 Flammang et al.. ..I64/1l9 3,015,848 1/1962 Hollfritsch ..18/30 LF 6 Claims, 9 Drawing Figures FOREIGN PATENTS OR APPLICATIONS 356,872 10/1961 Switzerland ..I8/3O LD 5' X X X X X X X X 2 1 W2 8 7 I r M 1 1 PATENTEB APR] 7 I973 SHEET 1 BF 4 v XXXX xxxx IXXXXXXO PATENTEBAPRIHQYS 3,727.. 674

sum 3 UF 4 The present invention relates to a low-pressure chillcasting device, notably for light alloys.

As a rule, low-pressure chill-casting processes are performed by using a crucible in which the metal to be cast is kept in the molten state and from which a transfer tube emerges and leads into a mould. This crucible is tightly closed so that a pressure can be exerted against the molten metal surface in order to force the metal up the transfer tube and into the mould cavity.

In hitherto known devices of this character the metal heating and casting steps are carried out within a compact, unitary structure, with the crucible located at the base of the vertical moulding press of which each plate carries a mould element. Now this rigid assembly comprising the press and the crucible is attended by many inconveniences, mainly of two orders:

I. Difficult access to the furnace and crucible both located beneath the press, and also to the various component elements of the mould, of which the shape control action is complicated by the vertical arrangement of these elements, and furthermore to the injection system connecting the crucible to the mould.

2. Injection of molten metal through the central potion of the lower mould, due to the relative position of these elements imposing this path as the shortest and the only one producing the minimum heat loss.

The low-pressure chill-casting light-alloy device according to this invention avoids the inconveniences set forth hereinabove and is concerned chiefly with a machine wherein the sealed enclosure comprising the crucible is separated from the press and moulds, and connected thereto through a detachable lateral casting duct, the arrangement of this duct being such that a regular feed of molten metal is obtained irrespective of the shape of the casting to be obtained.

Other features characterizing this invention will appear from the description given hereinafter with reference to the attached drawing illustrating diagrammatically by way of example a few typical forms of embodiment of t the invention. In the drawing:

FIG. 1 is a general view Of the device of this invention;

FIG. 2 is a general view of a modified form of embodiment of the same device;

FIG. 3 is a detail view showing the movable plate in its upper position, the upper portion of the mould being inclined;

FIG. 4 shows a typical form of embodiment of the movable plate of the press in the device of this invention;

FIGS. 5 and 6 are a plane view from above and a section taken along the axis I-I of FIG. 5, respectively, showing the casting duct;

FIGS. 7 and 8 are two modified forms of embodiment of the moulding device as seen in cross-sectional views, and

FIG. 9 is a diagrammatic illustration of the device for controlling the pressure of the molten metal as a function of its level in said mould.

Referring to FIG. 1, it will be seen that the molten metal introduced into the tiller orifice 1 accumulates in the casting ladle 2 and is brought to its melting point by a source of heat shown only in diagrammatic form at 3.

The casting ladle 2 is placed into a sealed or fluid-tight enclosure 8 to be referred to as the furnace" in the following disclosure; a tube or duct 4 dipping in this ladle 2 has its upper end connected to the casting tube proper 5, thus providing a fluid communication between the casting ladle 2 and the mould 6 disposed between the plates of a press 7. This arrangement also includes a pipe 9 opening into the sealed enclosure or furance 8 for delivering gas under pressure thereto. The furance 8 is contained in a cavity provided in close vicinity of the press 6 and mounted on wheels to facilitate its movements.

During the operation of the device, the gas pressure exerted within the enclosure 8 against the surface of the molten metal causes the latter to rise within the I connecting duct 4 and via the casting tube 5 into the mould 6.

Particular attention may be given to the relative position of the melting injection device and moulding device. Since these two devices are arranged separately, the access to their component elements is greatly facilitated.

In the case of the furnace 8 which is mounted on wheels the loading, removal of slag, treatment of the melt, repair and maintenance works if necessary, are also much easier to achieve.

Similarly, as the press 7 is free of the hitherto unavoidable limitations imposed by the presence of the furnace in the same structure, it can be arranged differently with a view to improve the access to its various component elements and reduce the overall dimen sions of the lower plate.

Thus, since in the conventional arrangements the central portion of this lower plate was partially occupied by the casting duct arid its ancillary implements, a problem of cumbersomeness had to be solved in connection with the position of the ejectors and retractable cores. Moreover, as the casting duct was formed within the plate mass, it was hardly accessible and therefore the cleaning of inclusions likely to accumumate therein during the metal cooling period constituted another difficult problem.

According to this invention, the injector is secured laterally, directly to the lower portion of the mould, thus freeing the lower plate of the press. Consequently, in case of clogging or damage, an operator can rapidly remove the casting tube 5 and possibly replace the faulty component. This removal is facilitated on the other hand by the mobility of the furnace 8 which is intended for this purpose.

FIG. 2 illustrates a modified form of embodiment of the arrangement of FIG. I, wherein the moulding device is inclined, the furnace and its associated elements remaining in the above-mentioned position. This arrangement is obtained by inclining the press on the frame structure 11 adapted to be set in the desired oblique position through suitable means (not shown), by pivoting about the axis 10. Shoes as shown diagrammatically at 12 carry the movable assembly 13 of the press as well as the mould overhang. This arrangement is particularly advantageous when making large chillcastings such as cylinder-blocks of automotive engines. In fact, when stripping these castings, these can easily be removed and transferred to another station by using a simple hoisting means acting in the direction A.

Moreover, the optical control or checking of the condition of the upper part of the mould is greatly facilitated.

The upper plate of the press modified as shown in FIG. 3, for the same purpose, can be used in the case of devices similar to the one illustrated in FIG. 1. In this alternate structure, the upper plate 14 of the press which carries the mould section 15 can be inclined by pivoting about the horizontal axis 16 under the control of a piston and cylinder actuator 17 connected with one end to said plate and with the other end to the press frame structure.

With this arrangement, after the moulded part has been ejected the upper portion of the mould is inclined to permit a easy inspection of its impressions and, if necessary a rapid intervention for repairing or reconditioning them.

This device may be provided with a symmetrically disposed second cylinder and piston actuator 17' which, when operated in lieu of actuator 17, would rotatably drive in the same manner but in the opposite direction the plate 14 about the axis 16' and thus permit a supervision of the mould impressions by an operator positioned on the left-hand side of the assembly as shown in FIG. 3. The plate 14 is locked in the horizontal position in the known manner by using means shown only diagrammatically at 18 and 18'.

According to a preferred embodiment, the upper plate 7- of the press is shaped as illustrated in FIG. 4. This form of embodiment is particularly applicable in the case of an inclined press (see FIG. 2) and its purpose is to avoid abnormal stresses from developing during the movements of the movable plate 3 along the uprights 7 of the press. These stresses resulting from the particular position of the press (FIG. 2) and also from the differential expansion of its component elements which are detrimental to the proper guiding of the plate and also to the useful life of the assembly.

To this end, the movable plate 13 is rigidly assembled to the press uprights by means of a set of four straps l9 pivoted to one point along the relevant diagonals of plate 13 and supporting sliding rings 20 adapted to slide freely in the direction of the plate diagonals, these two members 19, 20 being secured in the known fashion with each other, for example by means of grooves formed in one of them and tenons carried by the other member. These sliding rings 20 are displaceable along the press uprights and when their position is such that the distance between the uprights is modified in relation to their normal position, this change in mutual spacing is absorbed by the straps 19 which can rotate about their axis 21 and move along the rings 20 in the direction of the plate diagonals, due to the provision of a gap 22 to this end.

FIGS. 5 and 6 illustrate the casting duct 5 of the chillmoulding device of this invention.

This duct 5 is a cheap, easy-to-fit cast-iron member; these properties take however due account of the fact that this member is a wearing piece exposed to sudden heat shocks so that it is subject to relatively frequent temperature changes. This duct comprises two sections: the upper section 5a having a device 5c for injecting nitrogen or any other inert gas adapted to prevent the formation of oxides during the introduction of metal; and the lower portion 5b comprising a cavity 24b of same shape as the cavity 24a formed in the other mould section 5a. The volume of the resultant cavity 24"decreases along the longitudinal axis of the duct, in the direction away from the metal inlet 23 extending towards the furnace 8. With this arrangement, a practically constant pressure is maintained along the entire longitudinal axis of cavity 24.

Branched off this cavity 24' are a pair of ducts 25, 25' leading to a same mould impression, or to a plurality of impressions differently distributed about this casting duct 5.

One of the original characteristics of this invention lies in the fact that a plurality of feed ducts 25 are caused to open into the same mould impression or cavity, at properly selected locations, in order to ensure a regular or uniform distribution of molten metal along the impressions or cavities, without leaving any blind spot or corner therein.

FIGS. 7 and 8 illustrate two arrangements of this casting duct 5 in the moulding press 7.

Referring to FIG. 7, the casting duct 5 is formed in a compartment provided in an eccentric portion of plate 26 and of one of the two mould sections 27, before opening into a zone adjacent to the mould impression; the molten metal flowing from duct 5 penetrates into the moulding cavity through one or a plurality of openings 25 properly disposed according to the abovedescribed arrangement.

The casting duct 5 comprises in the vicinity of its outlet a plurality of burners 33 adapted to keep the temperature at a level higher than the melting temperature of the molten metal injected thereby in order to prevent any clogging of duct 5. To this end the component elements of this duct are made with the smallest possible wall thickness consistent with the proper and necessary mechanical strength requirements of the assembly. However, if for instance as a consequence of a machine hold up this clogging occured, it would be an easy matter to have access to the inoperative member, due on the one hand to the absence of the melting-injection device at the bottom of the press, and on the other hand to the size of the opening 28 formed in the plate.

FIG. 8 shows a modified form of embodiment of the preceding device, which comprises the casting duct 5, the reheaters 33, the ducts 25 for injecting the molten metal into the mould 28, 28', disposed between the supports 27 and the press plates 26.

The difference lies in the fact that the metal is injected simultaneously into two rows of moulds 28, 28. In this case the injection duct still comprises two sections 50 and 5b each disposed in a trough 29, 29' formed in the chill mould 27 or, possibly, in the press plate 26.

As already described hereinabove, the volume of this injection duct decreases along its longitudinal axis in the direction away from the source of molten metal, and opens in the same fashion into a side face of the chill mould or plate press. The accessibility of the duct 5 in case of repair is also very easy; another advantage deriving from this arrangement is the great number of castings that can be made simultaneously (for example in the case of cylinder heads and pistons of internal combustion engines which are cast according to the socalled cluster method).

The device illustrated in FIG. 9 is adapted to permit a proper control of the pressure P prevailing in the furnace 8 and therefore of the pressure of the molten metal within the mould 6.

To this end, two members 30, 31 responsive to the presence of metal are disposed within the moulding en closure; these members may consist for example of electrodes adapted to close a circuit when the molten metal rises to their level.

The electrode 31 is located at the lower portion of the moulding impression and its function is to close a circuit for reducing the metal temperature when said electrode contacts the metal surface to prevent, at the end of the mould filling operation, the occurence of detrimental effects such as hammering, burrs, soaking of sand cores, etc. This circuit and the pressure regulating means are illustrated in block form at 32.

In contrast thereto the electrode 30 is provided for increasing the metal pressure within the mould when the electrode contacts the metal within the mould, in order to supply metal to the pipe developing during the solidification. This device, mounted on anyone of the various forms of embodiment of the moulding device of this invention, will permit a close coupling between the two sections separated under the conditions set forth hereinabove.

Of course, the above description is given by way of example only and should not be construed as limiting the scope of the invention since many modifications may be brought thereto without departing from the basic principles of the invention; furthermore, many details of the forms of embodiment shown, described and suggested herein could be replaced by equivalent means without departing from the spirit and scope of the invention.

We claim:

1. A device for chill-moulding light alloy castings under low pressure conditions, comprising:

a first section comprising a fluid-tight enclosure and a crucible disposed within said enclosure, said crucible adapted to be filled with molten metal, second section comprising a mould comprising a plurality of mould sectionsassembled in a press and attached to one of an upper plate or lower plate of said press, said press having a movable plate secured to uprights along which said movable plate is adapted to slide through four straps disposed at the corners of said movable plate, said straps comprising on their inner faces groove means engaged by matching portions of rings formed with a pair of flat faces for permitting movement of said plate along the press uprights while providing the plate with a certain amount of lateral play, said two sections movable in relation to each other,

a casting duct and a casting connecting tube providing fluid connection between said crucible in said first section and said mould in said section, said casting duct and said casting connecting tube adapted for easy removal and heating, and

means for developing air pressure within said air pressure within said fluid-tight enclosure for forcing molten metal from said crucible into said mould through said casting duct.

2. A device according to claim 1, wherein said mould includes a chill-mould cavity receiving said casting duct, and said cavity includes a plurality of burners adapted to keep the temperature of said duct above the melting temperature of metal injected through said duct.

3. A device for chill-moulding light alloy castings under lowpressure conditions, comprising: i

a first section comprising a fluid-tight enclosure and a crucible disposed within said enclosure, said crucible adapted to be filled with molten metal,

a second section comprising a mould comprising a plurality of mould sections assembled to one of an upper plate or lower plate of a press,

said two sections movable in relation to each other,

a casting tube and a casting connecting tube providing fluid connection between said crucible and said mould, and

means for developing air pressure within said fluidtight enclosure for forcing molten metal from said crucible into said mould through said casting tube, thereby operating said mould,

said casting tube comprising relatively thin-walled cast iron and opening into said mould which is a chill mould at a point near the mould cavity and widening at its end to form a longitudinal cavity having a volume decreasing; toward the end opposite the metal feed opening, and molten metal supply ducts branched off said cavity for ensuring a proper and uniform distribution of molten metal to any shape of casting to be obtained.

4. A device according to claim 1, characterized in that the casting duct comprises relatively thin-walled cast-iron and includes means for supplying nitrogen or other inert gas thereto, and opens into the mould at a point located near the moulding impression and widens at its end to form a longitudinal cavity having a volume decreasing towards the end opposite to the metal feed opening, and molten metal supply ducts branch off said cavity for ensuring a, proper and uniform distribution of molten metal to any shape casting to be obtained.

5. A device according to claim 3, wherein the chill mould cavity receiving the casting duct includes a plurality of burners for keeping the temperature of said duct above the melting temperature of metal injected through said duct.

6. A device for chill-moulding light alloy castings under low-pressure conditions, comprising:

a first section comprising a fluid-tight enclosure and a crucible disposed within said enclosure, said crucible adapted to be filled with molten metal,

a second section comprising a mould comprising a plurality of mould sections assembled to one of an upper plate or lower plate of a press, wherein said press comprises a movable plate secured to uprights along which it is adapted to slide through four straps disposed at the corners of the movable plate, said straps comprising on their inner faces groove means engaged by matching portions of rings formed with a pair of flat surfaces and permitting movement of said plate along said uprights and providing said movable plate with a certain amount of lateral play,

said two sections movable in relation to each other,

a casting tube and a casting connecting tube providchill mould at a point near the mould cavity and ing fluid connection between said crucible and widening at its end to form a longitudinal cavity Sa1dm0l11and having a volume decreasing toward the end opmeans for developing air pressure within said fluidtight enclosure for forcing molten metal from said crucible into said mould through said casting tube, thereby operating said mould, said casting tube comprising relatively thin-walled cast iron and opening into said mould which is a posite the metal feed opening, and molten metal supply ducts branched off said cavity for ensuring a proper and uniform distribution of molten metal to any shape of casting to be obtained. 

1. A device for chill-moulding light alloy castings under low pressure conditions, comprising: a first section comprising a fluid-tight enclosure and a crucible disposed within said enclosure, said crucible adapted to be filled with molten metal, a second section comprising a mould comprising a plurality of mould sections assembled in a press and attached to one of an upper plate or lower plate of said press, said press having a movable plate secured to uprights along which said movable plate is adapted to slide through four straps disposed at the corners of said movable plate, said straps comprising on their inner faces groove means engaged by matching portions of rings formed with a pair of flat faces for permitting movement of said plate along the press uprights while providing the plate with a certain amount of lateral play, said two sections movable in relation to each other, a casting duct and a casting connecting tube providing fluid connection between said crucible in said first section and said mould in said section, said casting duct and said casting connecting tube adapted for easy removal and heating, and means for developing air pressure within said air pressure within said fluid-tight enclosure for forcing molten metal from said crucible into said mould through said casting duct.
 2. A device according to claim 1, wherein said mould includes a chill-mould cavity receiving said casting duct, and said cavity includes a plurality of burners adapted to keep the temperature of said duct above the melting temperature of metal injected through said duct.
 3. A device for chill-moulding light alloy castings under low-pressure conditions, comprising: a first section comprising a fluid-tight enclosure and a crucible disposed within said enclosure, said crucible adapted to be filled with molten metal, a second section comprising a mould comprising a plurality of mould sections assembled to one of an upper plate or lower plate of a press, said two sections movable in relation to each other, a casting tube and a casting connecting tube providing fluid connection between said crucible and said mould, and means for developing air pressure within said fluid-tight enclosure for forcing molten metal from said crucible into said mould through said casting tube, thereby operating said mould, said casting tube comprising relatively thin-walled cast iron and opening into said mould which is a chill mould at a point near the mould cavity and widening at its end to form a longitudinal cavity having a volume decreasing toward the end opposite the metal feed opening, and molten metal supply ducts branched off said cavity for ensuring a proper and uniform distribution of molten metal to any shape of casting to be obtained.
 4. A device according to claim 1, characterized in that the casting duct comprises relatively thin-walled cast-iron and includes means for supplying nitrogen or other inert gas thereto, and opens into the mould at a point located near the moulding impression and widens at its end to form a longitudinal cavity having a volume decreasing towards the end opposite to the metal feed opening, and molten metal supply ducts branch off said cavity for ensuring a proper and uniform distribution of molten metal to any shape casting to be obtained.
 5. A device according to claim 3, wherein the chilL mould cavity receiving the casting duct includes a plurality of burners for keeping the temperature of said duct above the melting temperature of metal injected through said duct.
 6. A device for chill-moulding light alloy castings under low-pressure conditions, comprising: a first section comprising a fluid-tight enclosure and a crucible disposed within said enclosure, said crucible adapted to be filled with molten metal, a second section comprising a mould comprising a plurality of mould sections assembled to one of an upper plate or lower plate of a press, wherein said press comprises a movable plate secured to uprights along which it is adapted to slide through four straps disposed at the corners of the movable plate, said straps comprising on their inner faces groove means engaged by matching portions of rings formed with a pair of flat surfaces and permitting movement of said plate along said uprights and providing said movable plate with a certain amount of lateral play, said two sections movable in relation to each other, a casting tube and a casting connecting tube providing fluid connection between said crucible and said mould, and means for developing air pressure within said fluid-tight enclosure for forcing molten metal from said crucible into said mould through said casting tube, thereby operating said mould, said casting tube comprising relatively thin-walled cast iron and opening into said mould which is a chill mould at a point near the mould cavity and widening at its end to form a longitudinal cavity having a volume decreasing toward the end opposite the metal feed opening, and molten metal supply ducts branched off said cavity for ensuring a proper and uniform distribution of molten metal to any shape of casting to be obtained. 